Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/02—Analysing fluids
  • G01N29/022—Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/02—Food
  • G01N33/10—Starch-containing substances, e.g. dough
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
  • G01N17/008—Monitoring fouling
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/02—Analysing fluids
  • G01N29/036—Analysing fluids by measuring frequency or resonance of acoustic waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/26—Oils; Viscous liquids; Paints; Inks
  • G01N33/28—Oils, i.e. hydrocarbon liquids
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
  • G01N11/10—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/02—Indexing codes associated with the analysed material
  • G01N2291/025—Change of phase or condition
  • G01N2291/0256—Adsorption, desorption, surface mass change, e.g. on biosensors
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/02—Indexing codes associated with the analysed material
  • G01N2291/028—Material parameters
  • G01N2291/02818—Density, viscosity
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/04—Wave modes and trajectories
  • G01N2291/042—Wave modes
  • G01N2291/0422—Shear waves, transverse waves, horizontally polarised waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/04—Wave modes and trajectories
  • G01N2291/042—Wave modes
  • G01N2291/0426—Bulk waves, e.g. quartz crystal microbalance, torsional waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
  • G01N9/002—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis

Definitions

• specialty chemicals to a multitude of industrial processes is desirable and often required for efficient, profitable, and safe operation of the processes.
• specialty chemical treatments to such processes can help to reduce process fouling, corrosion, and foaming, among other things.
• These treatment chemicals are added to the processes at concentrations ranging from parts-per-billion to percent levels.
• the treatment dosage is often determined by monitoring changes in process parameters that correspond to the addition of the specialty chemical over time.
• those skilled in the art desire to relate dosage to changes in the process fluids.
• the means for determining dosage is often very time consuming as vital process parameters will many times only change meaningfully over a very long time period.
• the appropriate determination of the correct specialty chemical dosage can take several months. Once established, these dosages are set to a static value.
• the dosage does not increase or decrease as the fouling, corrosion, or foaming rate, for example, changes over time. This results many times in the addition of a wasteful excess of specialty chemical or worse, undertreatment with the specialty chemical.
• Examples of methods used to control the addition of specialty chemicals include the use of coupon analyses, off-line residual product testing, residual polymer testing, on-line pH monitors, conductivity monitors, and the like.
• Residual testing typically involves removing a sample fluid from the process and subjecting the sample for analyses at some site away from the process.
• the detection limit and variance of many methods is too high to provide accurate data for the control of the addition of specialty chemicals. That is, the sensitivity of on-line instrumentation is often not high enough to enable an operator to adjust the dosage of specialty chemical in real-time.
• a highly sensitive, in situ method that provides real-time feedback on the state of fluids in a process is desirable.
• quartz crystal microbalances to measure the amount of scaling, deposit formation or mass loss occurring in both hydrocarbon and aqueous systems. These devices operate by exciting a quartz crystal in contact with fluid (liquid or vapor) to a resonant frequency and then measuring the shift in resonant frequency due to the loss or accumulation of mass from/on the crystal surface. While successful in measuring the mass of deposits of hard, crystalline scale or foulant, we have found that traditional quartz crystal microbalance units are an unreliable indicator of many types of phenomena that occur in both aqueous and non-aqueous systems.
• quartz crystal microbalances do not accurately measure the mass of amorphous deposits formed from, for instance, biofouling, or the deposits of amorphous hydrocarbons on the surfaces of processing units or the like. Relying on traditional quartz crystal microbalances for these types of measurements produces inaccurate and unreliable data that cannot be used to control the feed of chemical used to correct a condition that is being measured.
• US-A-6 053 032 Examples of the use of typical quartz crystal microbalances for the measurement of crystalline scale formation in aqueous systems is found in US-A-6 053 032 corresponding to United States Patent Application, Serial Number 08/421,206 filed April 13, 1995. While the device and methods described in US-A-6 053 032 operates accurately, and gives excellent control when only crystalline scale is formed in a system, we have found that this device does not work in systems where amorphous, or combinations of amorphous and crystalline scale may form.
• devices such as that described in US-A-6 053 032 cannot be used to sense changes that occur in a fluid, such as a viscosity increase or decrease, density increase or decrease, the presence of an immiscible fluid, or the growth of an amorphous precipitate forming in the interior of a container containing a fluid. Accordingly, herein described is a method for the measurement of the properties of materials and process streams, and more particularly the measurement of the viscosity and density of materials, and more particularly to the accurate and rapid measurement of the viscosity and density of aqueous and non-aqueous fluids as well as mass deposition.
• the method employs a thickness-shear mode resonator device to determine mass accumulation, viscosity, and/or density of hydrocarbon solutions, vapors, and mixtures as well as mass accumulation, viscosity, and/or density of aqueous fluids.
• a thickness-shear mode resonator device to determine mass accumulation, viscosity, and/or density of hydrocarbon solutions, vapors, and mixtures as well as mass accumulation, viscosity, and/or density of aqueous fluids.
• the thickness-shear mode resonator devices may be used in aqueous systems to measure the growth and/or deposit of biological scales and both amorphous inorganic and organic scales. Additional uses of the thickness-shear mode resonator devices are disclosed hereinafter.
• Quartz crystal microbalances also sometimes called piezoelectric sensors, have been suggested for measuring the mass of matter depositing from a fluid medium, measuring the viscosity of a flowing fluid, determining the rate at which films are deposited, monitoring corrosion, and the like. While somewhat successful, quartz crystal microbalances measuring only shifts in resonant frequency often gave erroneous readings when used in industry under certain conditions. For instance, quartz crystal microbalances which were excellent at the measurement of hard adherent scale which actually deposited on the crystal and dampened the vibration of the crystal, often did not give proper results when amorphous or soft scale (biological growth, amorphous inorganic crystals, and the like) were deposited on the same crystal. This is because the devices relied only upon measuring shifts in resonant frequency. Therefore, these sensors would be useless as a means to control the addition of treatment chemicals like biocides and antipolymerants.
• Thickness-shear mode resonators useful in the practice of this invention are known to those in the art.
• a particularly useful thickness-shear mode resonator is disclosed in Granstaff et. al U.S. Patent 5,201,215. This device is able to determine the density-viscosity product of a given fluid.
• the quartz crystal portion of this thickness-shear mode resonator is substantially identical to the quartz crystal microbalances of the prior art. It is the manner in which the signal is processed which renders the use of the Granstaff thickness-shear mode resonators unique, and which allows these thickness-shear mode resonators to do what typical quartz crystal microbalances cannot do.
• the oscillator circuitry of the device described in Granstaff '215 provides not only a measure of resonant frequency, but also a measure of changes in resonant frequency amplitude which is sensitive to the physical properties of the fluid medium in which the crystal is immersed.
• a second type of thickness-shear mode resonator which is useful in the practice of this invention is disclosed by S. J. Martin et al. in Sensors and Actuators A 44 (1994) 209-218.
• This type of device utilizes a first sensor having a roughened surface and a second sensor having a smooth surface. By the use of this device it has been found possible to simultaneously determine and resolve mass deposition, fluid viscosity and density. By using both smooth and rough surfaces which respond differently to mass adhesion, it is possible to differentiate mass deposition and viscosity and density of a fluid in contact with the piezoelectric crystal of the thickness-shear mode resonator.
• the mass of a solid and/or the physical properties of a fluid may be determined when both the mass and the fluid contact the same quartz crystal by applying an oscillating electric field across the thickness of the quartz crystal microbalance in contact with a solid mass interposed between the quartz crystal microbalance and a fluid, measuring at least one resonant frequency of the quartz crystal microbalance, simultaneously measuring the admittance magnitude at the resonant frequencies, and correlating the resonant frequency and the admittance magnitude to obtain a surface mass density and a fluid viscosity-density product.
• an oscillating electric field may be applied across the thickness of a quartz crystal microbalance, sweeping a frequency over a range that spans at least one resonant frequency of the crystal, measuring the magnitude and phase of the admittance over the frequency range, correlating the admittance data to the frequency, and applying admittance/frequency correlation to an equivalent circuit model, contacting a solid mass and/or a fluid onto the crystal wherein the solid mass is interposed between the crystal and the fluid, repeating the steps of sweeping the frequency range that spans a resonant frequency, measuring the magnitude and phase of the admittance over that frequency range, and correlating the admittance data to the frequency and then applying the admittance/frequency correlation to the equivalent circuit model and then extracting the solid mass and fluid density-viscosity product from the correlated admittance/frequency data.
• the mass layer may be metals, metal alloys, salts, some rigid polymers, or ice, and that these solids may be applied to the quartz crystal microbalance by evaporation, electroplating, precipitation, or other chemical or thermodynamic reaction, there is no appreciation by Granstaff et al. that the method may be effectively utilized in the field of hydrocarbon processing or water treatment, or that the devices may be effectively utilized to control the addition of process additives in these areas.
• a method for the rapid measurement of the rate of biological growth and/or deposit of amorphous inorganic or amorphous organic scales occurring on a surface in contact with a fluid and controlling such rate, growth or deposit, said fluid being selected from the group consisting of a hydrocarbon fluid within a hydrocarbon processing unit and an industrial water contained in an industrial water system, which method comprises the steps of:
• the invention is applicable to the determination of the properties of both aqueous and non-aqueous systems.
• Among the principle uses for this invention are the determination of amorphous scaling, and biofouling in aqueous systems, the determination of amorphous organic fouling in hydrocarbon processes, the determination of fluid characteristics such as viscosity and density, the amount of sedimentation occurring in a tank or vessel and the rate at which such sedimentation occurs. As stated, these are only some of the applications of the invention in the fields of water treatment and hydrocarbon processing.
• water treatment herein is meant the prevention of amorphous inorganic scale, and biofouling on the surfaces in contact with a water supply or industrial water system.
• the invention as stated above is particularly useful in the determination of the rate of biological growth occurring in an aqueous system.
• water treatment as used herein is the separation of solids from fluids, either vapor or liquid, using either chemical and/or mechanical means, and the separation of oil from water, again, using either chemical and/or physical means.
• hydrocarbon processing means the transport of crude oil by pipeline, rail, barge, or tanker, and the processing of this crude oil into useful products by various means including desalting processes, distillation, cracking, and other means to produce salable products, as well as the further treatment of such hydrocarbon products in the chemical processing industries including the production of such valuable materials as styrene, butadiene, isoprene, vinyl chloride, ethylene, propylene, acrylonitrile, acrylic acid, alkyl acrylates, and the resultant polymeric materials formed from such materials.
• the subject invention may be employed in any situation where it is desired to know the rate at which amorphous organic foulants are formed on the surfaces of heat transfer equipment, flow lines, storage tanks, and the like.
• the thickness-shear mode resonator may be installed to achieve the method of the subject invention at any location in a process where amorphous organic fouling, amorphous inorganic scaling, or microbiological growth can be expected, or where a change in the characteristics of a fluid may indicate such a processing problem which can be corrected through the addition of a chemical treatment. Because the use of this invention allows for real-time data, control over amorphous scaling, fouling and microbiological growth is rapidly and accurately achieved in an unprecedented manner. The inventors herein know of no other technique that can simultaneously provide instantaneous, real-time mass deposition and fluid property data to control the feed of water treatment chemicals and/or hydrocarbon processing treatment chemicals in accordance with the method of the present invention.
• the thickness- shear mode resonator device may be placed adjacent to the surface of the container holding the fluid or may be inserted into the container in any location where the fluid contained in the container is in contact with the quartz crystal surface of the thickness-shear mode resonator device.
• the container utilized may be advantageously selected from the group consisting of hydrocarbon processing units, hydrocarbon storage tanks, pipelines, or transport vessels such as barges, ships, and railcars.
• the thickness-shear mode resonator device may be placed into the system on a permanent basis, it is also possible to place such a device into a system on a temporary basis to determine whether a correcting chemical should be added.
• thickness-shear mode resonator device While in the above description the term thickness-shear mode resonator device has been used in the singular form it is often times desirable to use more than one thickness-shear mode resonator device in a given system. As such, the singular form of the term thickness-shear mode resonator is used herein to include herein one, two, or multiple thickness-shear mode resonator devices. This allows for additional control of the system. The use of multiple thickness-shear mode resonator devices is especially important when the devices are used to determine sediment in a tank, emulsion breaking efficiency not covered by the appended claims, the level of foam in a vessel, the level of each of two or more distinct phases in a container not covered by the appended claims, and the like.
• the use of this invention allows for the real-time determination of parameters which effect the aqueous system.
• amorphous scale formation, or biological fouling can be detected long before such scale, or biological fouling can be visually detected in the system, and long before other methods of measurement would provide the same information.
• problems occurring in the system are detected much earlier than with traditional methods, and corrective action through the use of appropriate scale inhibitors or microbiocides can be initiated immediately to control the problem.
• superior control of industrial systems can be achieved.
• the thickness-shear mode resonator also operates in real-time which avoids problems with basing chemical feed on coupon analyses which are composite (integrated over time) sampling. This type of monitoring does not indicate upset conditions as they occur.
• the invention determines a fouling, and/or biological growth condition occurring on the surface of a hydrocarbon processing unit in contact with a hydrocarbon fluid (either a liquid or gas) contained in the hydrocarbon processing unit, and steps may instantaneously be taken to correct such condition.
• a hydrocarbon fluid either a liquid or gas
• the thickness-shear mode resonator device is preferably placed on the surface of the hydrocarbon processing unit so that the quartz crystal of the thickness-shear mode resonator is in contact with the fluid, in this inventions broadest sense, it is only important that the quartz crystal surface of the thickness-shear mode resonator device be in contact with the fluid to be measured.
• the equipment may be a compressor, reboiler, heat exchanger, purification column, hold vessel, or reactor.
• the invention is applicable to almost any hydrocarbon processing unit including those processing alkenes and alkynes (e.g. ethylene, propylene, styrene, acrylonitrile, acrylic acid, alkyl acrylates, vinyl chloride, butadiene, and isoprene) as well as downstream units that further process the alkenes and alkynes.
• Chemical additives that may be controlled include scale inhibitors, antifoulants, antifoams, antipolymerants, and the like. It will be readily apparent that this invention is not limited to any specific type of specialty chemical additive to any particular process.
• each of the embodiments of the invention described herein takes advantage of the thickness-shear mode resonator.
• the thickness-shear mode resonator is mounted so that the exposed side of the quartz is in direct contact with the fluid circulating in the system.
• it is important to take into account the fluid turbulence caused by the insertion of the thickness-shear mode resonator. Accordingly, when measuring fouling, scaling, or even the viscosity or other characteristic of a fluid, it is often advantageous to mount the thickness-shear mode resonator flush with the surface of the container or pipe through which the fluid passes.
• a portable thickness-shear mode resonator could be utilized.
• the portable fixture would be easily inserted into the fluid or head space of a tank, drum, or open vessel.
• the quartz crystal surface of the thickness-shear mode resonator can be as small as desired, or as large as practical. Quartz crystal microbalances of the type required to build the thickness-shear mode resonators useful in the practice of the subject invention are available in various sizes from a variety of commercial sources.
• One of the features of this invention is that the thickness-shear mode resonator allows for the rapid and accurate determination of a condition and the change in a parameter to control the condition.
• the invention is usable over a wide variety of pressures and temperatures. When used at under high pressures, it is preferred that both sides of the quartz crystal be pressure equalized. When only one side of the crystal is subjected to high pressure, distortion of the crystal may take place causing inaccurate readings.
• the invention is useful over a wide range of temperatures ranging from substantially below freezing to as high as the melting point of the electrical connections used to receive the signal from the quartz crystal.
• the device is not directly useful in the pyrolysis section of for instance an ethylene furnace, the device is usable at points exiting the furnace.
• the thickness-shear mode resonator is when such device controls the addition of a specialty chemical material which is designed to ameliorate or otherwise moderate a condition, for example the turning on or off of a pump containing microbiocide, scale inhibitor, fouling inhibitor, or the like.
• Methods for the development of circuits controlling pumps using the output of the thickness-shear mode resonator device are well known in the art.
• Such circuits use the signal, after the determination through calibration of a desired signal level from the thickness-shear mode resonance device, to drive such pump means.
• the signal can also be utilized to open or close blow-down valves in the case of a cooling water or boiler water system, or to increase or decrease the flow of a hydrocarbon fluid passing through a given system.
• an oscillator circuit is utilized to maintain a constant potential across a piezoelectric crystal (quartz crystal) to provide stable oscillations.
• the output is measured and processed in accordance with the general principles elucidated in U.S. 5,201,215.
• the "raw-data" output, frequency shift and damping voltage obtained by using the circuitry described in Granstaff, and elsewhere in Wessendorf U.S. 5,416,448, is also a measure of the changes occurring on the sensor surface and may be used directly without conversion to physical property values. This technique may be especially useful where it is difficult to obtain accurate mass or fluid property results.
• the chemical additive could be controlled by empirical observation of the frequency and/or voltage output.
• This raw data is also of course a measurement of the viscosity-density and mass components of the fluid in contact with the piezoelectric device, and our invention encompasses the control of specialty chemical processes using either the raw frequency shift and voltage data, or the viscosity-density and mass components calculated from the raw data.
• Acrylonitrile is typically recovered from the gaseous effluent of catalytic reactors by extraction with water in a column typically known as an absorber. Hydrogen cyanide and acrylonitrile are selectively extracted from the effluent and this mixture is boiled overhead in a recovery column to a set of towers where the acrylonitrile is isolated as a pure component by a series of distillations. Residual organics in the flow from the bottom of the recovery column are removed by distillation in the stripper column and most of the remaining water is sent back to the absorber in this cyclic recovery process. Efficient operation of the recovery process is limited by fouling that occurs in the process, especially on heat transfer equipment like reboilers, heat exchangers and distillation towers.
• a quartz crystal sensor of the type described herein would be installed in critical locations in the acrylonitrile purification process. Typical locations at which thickness-shear mode resonators would be installed would include the solvent water stream just prior to a heat exchanger. This sensor would be installed so as to protrude into the solvent water stream.
• the crystal would be driven by an oscillator circuit on the outside pipewall. Oscillator and crystal would be connected via a hermetic rf circuit on the outside pipewall. The oscillator would provide a frequency and an amplitude output. Changes in resonant frequency would be indicative of changes in mass on the crystal surface and/or changes in fluid properties. Changes in amplitude are reflective of crystal damping.
• the measurements of crystal damping could be an especially useful measurement because damping is affected by the viscoelastic nature of the deposit, and the deposits in an acrylonitrile process can be highly viscoelastic. Viscoelastic deposits in the acrylonitrile process would preclude the use of other quartz crystal microbalance sensors that fail to account for the influence of viscoelastic properties. Damping is also important to resolve changes in mass from changes in fluid properties since resonant frequency is sensitive to each. Traditional quartz resonator sensors would not satisfy this requirement since these devices are sensitive to changes in resonant frequency only. The sensor used herein is useful in controlling the process because the associated oscillator circuit is sensitive to changes in resonant frequency and changes in amplitude (damping voltage).
• oscillator output would be measured by a frequency meter and a voltmeter that were each connected to a personal computer. Other measurements collected would include time and temperature.
• the computer would be used to calculate and plot the rate of mass accumulation on the crystal surface. This rate would then be determined prior to the injection of antifoulant to the process, and the deposition rate in the untreated solvent water would be proportional to the rate of fouling in the heat exchanger. This rate would be continually monitored over time as antifoulant was injected into the system. The antifoulant dosage would then be adjusted until the rate began to change. This would be manifested on the computer by a change in slope for the line that results from a plot of deposited mass versus time.
• the antifoulant dosage could be slowly adjusted until the slope of this line approached zero (no detectable deposition over a given time interval) to obtain an optimized antifoulant dosage.
• the optimized dosage would be established by actual real-time measurement rather than indiscriminate variables that are easily affected by other process parameters. At any time during the run, if deposition increased, the antifoulant rate would be increased to compensate for the higher fouling rate.
• a small slip stream taken from the acrylonitrile recovery process could be utilized.
• overall deposition of solids in the bulk solvent water would overwhelm the thickness-shear mode resonators.
• a small flow of solvent water would be diverted to a flow cell containing the thickness-shear mode resonator.
• Deposition of solids from the slip stream would be proportional to deposition from the bulk solvent water provided that process parameters like temperature and pressure were maintained at constant levels.
• the flow cell may be heated by means such as heater rods, heat tape, steam, or other conventional means.
• the addition of a back pressure regulator to the slip stream line to maintain a constant pressure could also be useful.
• the thickness-shear mode resonator in the flow cell would be attached to an oscillator circuit outside of the flow cell and slip stream tubing. The oscillator output would be used as above to calculate the deposition rate and optimize antifoulant feed.
• a microprocessor could be substituted for components like the voltmeter and frequency meter.
• the microprocessor would make the devices more convenient to work with and would allow the use of data loggers and laptop computers. Output of the microprocessor in this case would be interfaced with the laptop computer or datalogger.
• the computer would be used to automatically control the pumpstroke on a pump adding antifoulant to the acrylonitrile process.
• the computer would be programmed to adjust pumpstroke by a certain degree for a proportional change in the rate of solid deposition on the crystal surface. When the fouling rate drops to zero, the computer would direct the pump to hold constant at its present pumpstroke or to reduce pumpstroke by a certain percentage. In this manner, chemical antifoulant dosage would be automatically optimized.
• the thickness-shear mode resonator would also be useful in the control of antifoulants to other hydrocarbon processing operations.
• this hypothetical example discloses the use of the thickness-shear mode resonator to control antifoulant addition to the caustic wash system of an ethylene plant.
• the thickness-shear mode resonator would be installed in the tower bottom fluids. Detection of solids in the tower bottoms would be indicative of the amount of foulant formed during washing of the hydrocarbon gas. Response from the sensors would be used to set the optimum dosage of caustic tower antifoulant required to eliminate fouling in the caustic tower. The detection of little, or no solids in the flow from the tower bottoms would determine the optimum antifoulant dosage.
• Thickness-shear mode resonators may be placed in the vapor space of towers such as primary fractionators, depropanizers, debutanizers, and butadiene purification columns.
• the thickness-shear mode resonators would be sensitive to the formation of viscoelastic polymer in the vapor phase which would deposit on the resonators.
• the deposition of a thin, viscoelastic film of foulant would be detectable using the oscillator circuitry described above. If formation of foulant on the crystal was detected, then the dosage of vapor phase antifoulant could be adjusted accordingly. In this way, the exact amount of antifoulant required to control vapor phase fouling could be determined.
• Hydrocarbon recovery towers also foul in the liquid and gaseous phases. Placing the thickness-shear mode resonators described above into the liquid tower bottoms would help to detect solids that deposit in the tower bottoms and in associated reboilers. These sensors could be used to control the amount of antifoulant that is added to the tower bottoms and to the reboilers. These additives are usually different from those added to control vapor phase fouling although the foulant is usually similar, a viscoelastic polymer that is insoluble in the liquid hydrocarbon.
• foulant is brought into a tower from another source.
• pyrolysis gasoline to a primary fractionator.
• spent caustic is washed with pyrolysis gasoline to remove benzene from the spent caustic prior to disposal of the spent caustic.
• the pyrolysis gasoline is sometimes used as reflux in the primary fractionator.
• aldol polymer is formed by the caustic-catalyzed polymerization of phenylacetaldehyde and other reactive carbonyl species in the pyrolysis gasoline. Any soluble gum formed in this process is carried to the primary fractionator, where some of the gum precipitates onto hardware within the primary fractionator.
• the thickness-shear mode resonator can be used for monitoring the growth of biofilm or "soft" deposits which cannot be measured using previously known quartz crystal microbalance devices.
• applications in aqueous systems that can be monitored using the thickness-shear mode resonator include pulp and paper processes where microbiological growth presents a problem, cooling water systems where bacteria and algae growth can present significant problems and certain waste treatment systems.
• the thickness-shear mode resonator device can simultaneously measure mass loading and fluid property changes such as density and viscosity in contrast to the earlier known device circuits, side stream sampling using the thickness-shear mode devices can be accurately used to monitor a microbiological fouling event in real time.
• the output of the thickness-shear mode resonator is directly related to the growth of the biofilm and may be used to control a chemical feed pump. Appropriate control algorithms may be developed which will ensure that the film growth rate remains within acceptable limits. Without thickness-shear mode resonance devices, coupon sampling is the only direct measurement technique available. Coupon sampling, however, requires obtaining a composite sample over a period of time and does not report system upsets as they occur. Real-time monitoring afforded by the thickness-shear mode resonator will enable these upsets to be rapidly controlled by changing the chemical treatment dosage.
• the method of the present invention would enable on-line control of the addition of these treatment chemicals using sampling and control techniques described above.
• a thickness-shear mode resonator would be installed on the wall of a paper machine in contact with the furnish being used.
• the thickness-shear mode resonator would be calibrated to respond to an increase in biofilm mass occurring on the surface of its quartz crystal.
• the thickness-shear mode resonator Upon the deposit of a biofilm onto the surface of the quartz crystal, the thickness-shear mode resonator would send a signal indicative of the build up of biofilm. This signal would be amplified, and a pump feeding a water soluble microbiocidal product would be started. The feed of biocide would continue so long as the mass of deposit would increase, and would stop when the mass of deposit either decreased or held constant.
• the viscoelastic properties of the biofilm can also be used to monitor biofilm fouling.
• the paper machine would be kept substantially free of biological growth. Because of the sensitivity of the thickness-shear mode resonator, the microbiocide would be added at a rate required to reduce biological growth and reduce over-feeding the chemical. This would result in reduced chemical consumption.
• a thickness-shear mode resonator would be installed on the interior wetted wall of an industrial cooling tower.
• the thickness-shear mode resonator would be calibrated to indicate mass deposition on its surface, and the signal would be amplified and would be connected to a pump connected to a supply of commercially available industrial microbiocide.
• the pump would feed biocide material into the cooling tower.
• the thickness-shear mode resonator Upon noting microbiological growth, as evidenced by changes in the mass or viscoelastic properties of the sample, the thickness-shear mode resonator would send a signal indicating build up, triggering the pump and initiating the feed ofbiocide.
• biocide feed Upon noting no further buildup or a decrease in buildup, biocide feed would be terminated.
• a cleaner cooling tower would be obtained, and less biocide would be consumed and discharged over time.
• the examples presented herein are not intended to be all inclusive of all of the various applications in which the sensors may be employed. Those skilled in the art will readily determine that in addition to determining the rate of fouling of hydrocarbon systems and controlling such fouling, the sensors may also be utilized for such diverse applications as determining the rate at which microbiocide should be fed to finished products, and the rate at which chemical treatment should be applied to a hydrocarbon stream to maintain its fluidity and prevent fouling.

Landscapes

• Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Acoustics & Sound (AREA)
• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Environmental Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Biodiversity & Conservation Biology (AREA)
• Ecology (AREA)
• Environmental & Geological Engineering (AREA)
• Medicinal Chemistry (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)
• Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
• Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
• Investigating Or Analysing Biological Materials (AREA)
• Sampling And Sample Adjustment (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=24490021

Family Applications (1)

Country Status (22)

Families Citing this family (107)

Family Cites Families (15)

• 1996
  • 1996-03-25 US US08/621,402 patent/US5734098A/en not_active Expired - Lifetime
• 1997
  • 1997-01-01 IN IN525CA1997 patent/IN191903B/en unknown
  • 1997-03-24 WO PCT/US1997/004726 patent/WO1997036178A1/en active IP Right Grant
  • 1997-03-24 CA CA002222046A patent/CA2222046C/en not_active Expired - Fee Related
  • 1997-03-24 CN CN97190339A patent/CN1131431C/zh not_active Expired - Fee Related
  • 1997-03-24 NZ NZ329132A patent/NZ329132A/xx not_active IP Right Cessation
  • 1997-03-24 AT AT97917601T patent/ATE218707T1/de not_active IP Right Cessation
  • 1997-03-24 MX MX9709033A patent/MX9709033A/es unknown
  • 1997-03-24 BR BR9702225A patent/BR9702225A/pt not_active IP Right Cessation
  • 1997-03-24 ES ES97917601T patent/ES2174246T3/es not_active Expired - Lifetime
  • 1997-03-24 DE DE69713009T patent/DE69713009T2/de not_active Expired - Lifetime
  • 1997-03-24 JP JP53453497A patent/JP3876293B2/ja not_active Expired - Lifetime
  • 1997-03-24 AU AU25877/97A patent/AU718367B2/en not_active Ceased
  • 1997-03-24 KR KR1019970708508A patent/KR100467948B1/ko not_active IP Right Cessation
  • 1997-03-24 RU RU97121350/28A patent/RU2241986C2/ru active
  • 1997-03-24 EP EP97917601A patent/EP0829010B1/en not_active Expired - Lifetime
  • 1997-03-25 TW TW086103779A patent/TW363079B/zh not_active IP Right Cessation
  • 1997-03-25 AR ARP970101202A patent/AR006392A1/es active IP Right Grant
  • 1997-03-25 ID IDP970973A patent/ID16437A/id unknown
  • 1997-03-25 MY MYPI97001249A patent/MY119386A/en unknown
  • 1997-11-24 NO NO19975376A patent/NO321041B1/no not_active IP Right Cessation
• 1998
  • 1998-10-20 HK HK98111336A patent/HK1017922A1/xx not_active IP Right Cessation

Also Published As

Similar Documents

Legal Events